The invention relates to hot plugging in a Peripheral Component Interconnect (PCI) bus system.
In computer systems operating with PCI hot-plug capable buses, the system can be powered and running while PCI adapter cards are plugged into or removed from PCI hot-plug slots. The PCI hot-plug capability, defined in PCI Hot-Plug Specification, Revision 1.0, Oct. 6, 1997, PCI Special Interest Group, Portland, Oregon, is especially desirable in network computer systems. The hot-plug capability allows maintenance to be performed on a server in a network computer system without having to power down the server.
The PCI hot-plug model include multiple adapter card slots simultaneously tied to the PCI bus and often requires controllers to monitor and control power, bus and clock signals. The system also requires power and bus isolation devices for isolating the PCI hot-plug slots during hot-plug operation.
In one aspect, the present specification involves a hot-plug capable PCI bus system with only one device, such as a slot, coupled to each PCI bus. The PCI bus system is configured to interface with external devices, and includes hot-plug slots, PCI buses, and a bridge controller. The need for isolating the hot-plug slot from a PCI bus is reduced by having only one device attached to the bus. Therefore, the PCI bus can be turned off during the hot-plug operation.
The PCI cards that are plugged into the hot-plug slots are configured to interface.with the external devices by formatting and sending data to and from the external devices and the PCI bus system. The PCI buses channel data to and from the hot-plug slots. Each PCI bus connects to only one hot-plug slot.
The bridge controller is,capable of monitoring and de-activating a particular PCI bus connected to the selected hot-plug slot being serviced for hot-plug operation. During hot-plug operation, the selected hot-plug slot can be serviced while the other PCI buses are operating.
Another aspect involves a method for removing an adapter card from a selected hot-plug slot during hot-plug operation of a PCI bus. The method involves electrically disconnecting the adapter card from power supply and the PCI bus, quiescing adapter card activities, and de-activating PCI bus interface pins. An attention indicator for the selected hot-plug slot is driven to indicate that the hot-plug slot is off and the adapter card can be removed.
In a further aspect, a method for inserting an adapter card to a selected hot-plug slot during hot-plug operation of a PCI bus is disclosed. The method involves inserting the adapter card into the hot-plug slot, electrically connecting power to the adapter card, and re-activating PCI bus interface pins. A power indicator for the selected hot-plug slot can be driven to indicate that the hot-plug slot is on.
Other features and advantages will become apparent from the following description and drawings, and from the claims.